科研之友
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摘要
Improving the low-cycle fatigue (LCF) properties of additively manufactured Ti-5.6Al-3.8V alloy is critical in ensuring its service safety and represents a significant research challenge. This work discusses a solution that optimizes the alloy's microstructure and ductility by precisely controlling the over-saturated strengthening elements and heat treatment. This was accomplished using selective laser melting (SLM), heat treatment at 800 degrees C for 2 h, and furnace cooling on a Ti-5.6Al-3.8V alloy with tightly controlled Al, V, and O concentrations in a lower range. The results showed that the SLM-fabricated Ti-5.6Al-3.8V alloy, post-heat treatment, exhibited alpha laths with a width of -1.4 mu m and beta columnar grains with a diameter of -126 mu m, without experiencing coarsening or variant selection phenomena. The alloy balanced strength and ductility post-heat treatment with a UTS of 1015 MPa and an EL of 16.5% relative to the as-deposited state (UTS of 1199 MPa and EL of 11.9%). Notably, the LCF properties of the heat-treated SLM Ti-5.6Al-3.8V alloy are superior to those of other Ti-6Al-4V alloys produced by additive manufacturing and comparable to traditional forgings. At high strain amplitudes (1-1.5%), the fatigue life of this alloy was twice that of the Ti-6Al-4V forgings. Furthermore, we comprehensively analyzed the microstructure, strength, and ductility of the SLM Ti-5.6Al-3.8V alloy to elucidate the factors influencing its LCF properties. These findings provide a solid foundation for improving the LCF properties of additively manufactured Ti-6Al-4V alloy, thereby contributing to its safe and reliable use in critical applications.
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单位长安大学; 西北工业大学
